Pharmaceutical compounds



PHARMACEUTECAL ooMPoUNDs William A. Lott, Mapiewood, and John Krapcho, New Brunswick, N. 3., assignors to Olin Mathieson Chemical Corporation, New York, N. Y., a corporation of Virginia No Drawing. Application August 30, 1956 Serial No. 606,948

8 Claims. (Cl. 260-559) This invention relates to new diphenylacetamide derivatives and, more particularly, to compounds of the general formula wherein R is a lower alkyl radical of less than four carbon atoms (i. e., methyl, ethyl, propyl and isopropyl), R is lower alkyl (e. g., methyl ethyl, propyl, butyl and hexyl) or lower alkenyl (e. g., allyl, methallyl, 2-butenyl and 2-hexenyl); Y is a lower alkylene radical separating the nitrogen atoms by at least two carbon atoms and includes such radicals as ethylene, propylene, butylene and hexylene, whether branched or straight chained; and NB is dimethylamino, piperidino, pyrrolidino, morpholino, or N -methylpiperazino; and acid-addition salts thereof. The preferred compound is the one wherein R is ethyl, R is methyl, Y is ethylene and NB is dimethylamino.

Examples of suitable acid-addition salts of the free base compounds of this invention include the mineral acid salts, such as the hydrohalides (e. g., hydrochloride, hydrobromide and hydroiodide), the sulfate, the phosphate, and the organic acid salts, such as the citrate, tartrate, oxalate, ascorbate and succinate. (Pharmacologically acceptable acids are, of course, employed where the salt form is prepared for therapeutic use.)

The compounds of this invention can be prepared by'a variety of methods. One suitable method involves the reaction of u-halodiphenylacetyl halide (e. g., oc-chlorodiphenylacetyl chloride) with an alkylene diamine of the formula HR'N--YNB to give the intermediate orhalodiphenylacetamide, which is then treated with an alkanol or alkoxide of the formula ROA, wherein R is as hereinbefore defined, and A is hydrogen or alkali metal, to yield the final product. A second method involves the reaction of N-(NBY)NR'-benzilamide (see U. S. Patent No. 2,733,256) with a chlorinating agent (e. g., phosphorus oxychloride or phosphorus pentachloride) and interacting the cz-ChlOlObEl'lZilflIllidC, thus formed, with an alkanol or alkoxide of the formula ROA, wherein NB, Y, R, R and A are as hereinbefore defined. Another method involves the reaction of the same N"-(NBY)N-R'-benzilamide with an alkali metal or agent furnishing the same (e. g., sodamide) to yield the corresponding salt and then treating the salt with a lower alkyl halide, RX, wherein X is halogen. A fourth alternative method involves the reaction of oc-RO-diphenylacetyl halide (e. g., u-ethoxy-diphenylacetyl chloride) with an alkylene diamine of the formula 1 States Patent tralization with the desired acid or metathesis with a salt of the desired acid, respectively.

The following examples illustrate the invention:

EXAMPLE 1 N Z-dimethylaminoethyl -2-eth0xy-N methyl-2,2-

diphenylacetam ide hydrochloride (a) Preparation of N (2 dimethylaminoethyl) 2- ethoxy-N-methyl-2,2-diphenylacetamide.A solution of 265 g. of oz-chlorodiphenylacetyl chloride [1. Chem. Soc.,

64 (1947)] in 1.3 liters of benzene is stirred and treated concentrated to about 200 ml., cooled, dissolved in 500 ml. of water and treated with a solution of 60- g. of sodium hydroxide in 200 ml. of water. The liberated base is extracted with ether and dried over magnesium sulfate. The solution isfiltered and the solvent evaporated to yield a residue which is fractionated to give a colorless distillate; B. P. about -162 C. at 0.2 mm.

(b) Preparation of N (2 dimethylam inoethyl) 2- ethoxy-N-methyl-2,2-diphenylacetamide hydrochloride.- A solution of g. of the base obtained in section (a) in 200 m1. of absolute alcohol is treated with one equivalent of hydrogen chloride in 100 ml. of absolute alcohol. The resulting solution is diluted with 600 ml. of ether to yield a crystalline solid melting at about -192 C. After recrystallization from isopropyl alcohol, the colorless product melts at about 190-192 C.

EXAMPLE 2 N 2-dim ethylam ino'ethyl -2-m-eth0xy-N -methyl-2,2- diphenyla'cetamide hydrochloride A mixture of 29 g. of N-(Z-dimethylaminoethyl)-N methyl benzilamide hydrochloride and 18 g. of phosphorous pentachloride is stirred for five hours at room temperature. The mixture .is treated with 20 m1. of carbon tetrachloride and stirred for two hours at room temperature. 18 ml. of phosphorous oxychloride is then added, and the mixture is stirred for 2 hours at room temperature, followed by heating at 60-70 C. for one and one-half hours. The solvent and excess phosphorous oxychloride are removed under reduced pressure, and the residue is suspended in 150 ml. of methanol and refluxed for ten hours. The major part of the solvent is distilled, the'residue is dissolved in water and treated with excess potassium carbonate. Theliberated base is extracted with chloroform and dried over magnesium sulfate. The product is purified by distillation to give.

refluxed for four hours and the excess thionyl chloride;

removed under reduced pressure. The residue is dissolved in 200 ml. of benzene, stirred and treated dropwise with a solution of 14.4 g. of N-methyl-mo'rpholin'oethyla'mine in 501ml. of benzene at room temperature. The mixture is refluxed for two hours, cooledQaud' the Similarly, by substituting N -methylpiperazine or pyrrolidine for the morpholine in the procedure of Example 3, the corresponding N -methylpiperazino and pyrrolidino derivatives, respectively, are'obtained.

, 7 EXAMPLE 4 N (2 dimethylaminoethyl) 2 ethoxy N ethyl- 2,2-diphenylacetamide hydrochloride Interaction of29 g. of N,N-dimethyl-N-ethylethylenediaminelAnn. Chim, 6, 835 (1951)] in 100 ml. of benzene with a solution of 66 g. of a-chlorodiphenylacetyl chloride in 250 ml. of benzene, followed by treatment with absolute ethanol according to the procedure described in Example 1(a), gives about 39 g. of the base; B. P. about 174-177" C. (0.6 mm.).

The hydrochloride salt of this material, after crystallization from isopropyl alcohol, melts at about 185- 187 C.

EXAMPLE 5 N (2 dimethylaminopropyl) 2 ethoxy N methyl- 2,2-diphenylacetamide sulfate (a) Preparation of N (2 dimethylaminopropyl)- 2-ethoxy-N-methyl-Z,2-diphenylacetamide.A solution of 265 g. of u-chlorodiphenylacetyl chloride in 1.3 liters of benzene is stirred and treated dropwise with a solution of 116 g. of N-methyl-Z-dimethylaminopropylamine in 300 ml. of benzene While maintaining the reaction temperature at -25 C. The mixture is stirred at room temperature for two hours, refluxed for two hours, and then subjected to distillation collecting about 1 liter of distillate during the dropwise addition of 500 ml. of absolute alcohol. The residue is treated with 1 liter of absolute alcohol and stirred with reflux for eleven hours. The mix ture is concentrated to about 200 ml., cooled, dissolved in 500 ml. of water, and treated with a solution of 60 g. of sodium hydroxide in 200 ml. of Water. The liberated base is extracted with ether and dried over magnesium sulfate. evaporated to yield a residue which is fractionated to give a distillate of N-(Z-dimethylaminopropyl)-2-ethoxy- N-methyl-2,2-diphenylacetamide.

(b) Preparation of N (2 dimethylaminopropyl)-2- eth0xy-N-methyl-2,2-a'iphenylaceta mide sulfate.A solution of 50 g. of the base obtained in section (a) in 200 ml. of absolute alcohol is treated with one equivalent of sulfuric acid in 100 ml. of absolute alcohol. The resulting solution is diluted with 600 ml. of ether to yield a crystalline solid.

EXAMPLE 6 N (2 piperidinoethyl) 2 ethoxy N methyl- 2,2-diphenylacetamide hydrochloride The reaction of 26.5 g. of a-chlorodiphenylacetyl chloride with 14.2 g. of 2-piperidinoethylmethylamine [1. Chem. Soc., 1421 (1935 in benzene, followed by treatment with absolute alcohol, as described in Example 1(a), yields a colorless base which is then converted to a crystalline hydrochloride salt, by the procedure in Example 1(b).

EXAMPLE 7 N-allyl-N-(Z-dimethylaminoethyl) -2-ethoxy-2,2- diphenylacetamide hydrochloride The solution is filtered and the solvent 4 to give about 53 g. of colorless product; B. P. about 5863 C. at 25 mm.

(b) Preparation of N-allyl-N-(2-dimethylaminoethyl)- Z-ethoxy-2,2-diphenylacetamide hydr0chloride.A solution of 79.5 g. of ot-chlorodiphenylacetyl chloride in 390 ml. of benzene is stirred and treated dropwise with a solution of 38.5 g. of N-allyl-N',N'-dimethylethylenediamine in ml. of benzene. The mixture is refluxed and treated with absolute ethanol in the manner described in Example 1(a) to give about 76.5 g. of a colorless oil, B. P; about l70-175 C. (0.5 mm.). The hydrochloride salt, after crystallization from absolute alcohol, melts at about 208210 C.

The compounds of this invention are useful as analgesics. Thus, N-(Z-dirnethylaminoethyl)-2-ethoxy-N- methyl-2,Z-diphenylacetamide hydrochloride, for example, can be administered either perorally or intramuscularly in the same manner as meperidine hydrochloride for the alleviation of pain. The fact that the compounds of this invention display analgesic activity is surprising in view of the fact that the closely related 2-hydroxy derivatives [e. g., N-(Z-dimethylaminoethyl)-2-hydroxy-N-methyl- 2,2-diphenylacetamide hydrochloride] have virtually no analgesic activity.

The invention may be otherwise variously embodied within the scope of the appended claims.

We claim:

1. Compounds of the class consisting of: free bases having the general formula wherein R is a lower alkyl radical of less than four carbon atoms, R is selected from the class consisting of lower alkyl and lower alkenyl, Y is a lower alkylene radicalseparating the nitrogen atoms by at least two carbon atoms, and NB is a radical selected from the class consisting of dimethylamino, piperidino, pyrrolidino, morpholino and N -methylpiperazino; and the pharmacologically acceptable acid-addition salts thereof.

2. N [dimethylamino(lower alkyl)] 2 ethoxy-N- (lower alkyl)-2,2-diphenylacetamide.

3. A pharmacologically acceptable acid-addition salt of a compound of claim 2.

4. N (2 dimethylaminoethyl) 2 ethoxy-N-methyl- 2,2-diphenylacetamide. 5. A pha-rmacologically acceptable acid-addition salt of the compound of claim 4.

6. N-[dimethylamino(lower alkyl)]-2-ethoxy-N-allyl- 2,2-diphenylacetamide.

7. A 'pharmacologically acceptable acid-addition salt of the compound of claim 6.

8. N (2 dimethylaminoethyl) 2 ethoxy-N-methyl- 2,2-diphenylacetamide hydrochloride.

References Cited in the file of this patent UNITED STATES PATENTS 2,009,144 Miescher et al July 23, 1935 2,733,256 Krapcho et al. Jan. 31, 1956 FOREIGN PATENTS 438,659 Great Britain Apr. 25, 1935 OTHER REFERENCES Elsevier Publishin'g Co. Inc., New York, page 50 relied OIL 

1. A COMPOUND OF THE LESS CONSISTING OF: FREE BASES HAVING THE GENERAL FORMULA 